Theoretical ecology refers to several intellectual traditions. The tradition pursued in universities and scientific journals under the rubric of theoretical ecology addresses the probability distributions that govern the demography and biogeography of species; and, for example, the mathematics of competition.

To a large extent theoretical ecology draws on the genius of G. Evelyn Hutchinson and his students. Brothers H.T. Odum and E.P. Odum are seen as the true founders of modern Ecosytem Ecology . Robert MacArthur brought theory to community ecology . Daniel Simberloff was the student of E.O. Wilson, who collaborated with on "The Theory of Island Biogeography ", a seminal work in the development of theoretical ecology. Simberloff went on to add rigour to experimental ecology and was one of the stalwarts in the SLOSS debate (whether it is preferable to protect a 'Single Large or Several Small' reserves) and forced supporters of Jared Diamond's community assembly rules to defend their ideas through Neutral Model Analysis . Simberloff also played a key role in the (ongoing) debate on the utility of corridors for connecting isolated reserves (with Reed Noss taking the lead on the opposing side).

MacArthur's students Stephen Hubbell and Michael Rosenzweig combined theoretical and practical elements into works that extended MacArthur and Wilson's Island Biogeography Theory - Hubbell with his Unified Neutral Theory of Biodiversity and Biogeography and Rosenzweig with is Species Diversity in Space and Time .

Other key theoretical ecologists include Robert May, who has been described as being 'one of the best minds in ecology' and David Tilman .

Another tradition is the consideration of life and its interactions with environment from a metaphysical standpoint. An example question that has been addressed in this field is one posed by physicist Erwin Schrödinger who asked, "What is life?"

Theoretical biologist Robert Rosen tackled this question but reframed it in the process. In his 1991 book, Life Itself, Rosen suggests that a better question is, "Why are organisms different than machines?" His answer addresses the unfractionability, or self-causing unity, of life; he states "a material system is an organism if, and only if, it is closed to efficient causation." The supporting work behind this definition of life embodies his "relational theory of systems". The scientific paradigm behind this theory represents a radical departure from the mainstream mechanical and reductionist paradigm dating back to Newton and Descartes.

Theoretical ecologist Robert Ulanowicz builds on work by Rosen and others to develop a comprehensive "ecological metaphysic". In his book, Ecology, the Ascendent Perspective, Ulanowicz develops an ecological metaphysic and contrasts it with the older, mechanical Newtonian counterpart. In a 1999 article in the journal, BioSystems, Ulanowicz describes the Newtonian paradigm as one which treats systems as 1) deterministic and thus predictable, 2) closed to external influence and well-described with forces, 3) time-reversible, and 4) decomposable, fractionable or atomistic. He adds a 5th descriptor that states that "Newtonian laws are universal." In contrast, the ecological paradigm of systems he has developed treats systems as 1) indeterminate and thus unpredictable, 2) contingent or best described with propensities, 3) historical and time-irreversible, and 4) organic and not readily decomposable. He suggests that laws derived from an ecological metaphysic are "granular", hierarchical and scale-dependent rather than universal.

Rosen and Ulanowicz share the view that an understanding of life is not something readily gained by extension or extrapolation of a mechanical approach to systems. Instead, each has worked to develop a new paradigm that differs from the mechanical paradigm and then has attempted to demonstrate how this new paradigm is better for understanding and explaining the special properties and dynamics that life exhibits. If one were to reverse this process - to ask what implications this new ecological paradigm might have for understanding, conceiving or designing machines - the work of theoretical ecology may hold important insights for human technology and its evolution.